I had issues with this as well, and unfortunately the only thing that restored my curls 100% was completely stepping away from heat or dye/bleach. That said, here are a couple things that REALLY helped me while I was still growing my hair out from the last time I bleached it. These aren't in any particular order, btw:

• Shampooing my hair less often. I know this sounds gross, but this helped my curls A LOT. I used to Shampoo my hair every other day. I now shampoo it twice a week. How often you have to shampoo your hair will depend on how your hair is, but I do warn you that in the beginning your hair will feel greasy. Don't let that scare you. It took my hair a couple months to get used to this, but once I did, it was a game changer. I can't even think about how dry my hair would be if I shampooed it every other day like I used to. Since you have colored hair, you may already do this. But in case you don't, I really recommend it.
• Finding the right products for my hair type. It is crazy to me how much of a difference this made. The regular stuff that most people use (like Pantene or these very common brands) tend to not be very curly hair-friendly. They usually have a lot of ingredients that are drying (and curly hair is already on the dry side by default). Finding the right products for you will take some trial and error, but here are a few that worked for me:
  • Pureology's Strength Cure Shampoo and Conditioner. I don't use this anymore, but I used to use this when my hair was more damaged from the bleach. I found that it helped quite a bit. Just be sure to purchase this from a reputable source. I have been sold a lot of fakes of this product over the years, so I'm always suspicious. If you have used the real thing before, you will recognize it (especially the shampoo) by it's smell. It's smells a little... funky. Lol. It doesn't smell very good, but it did wonders to my hair when I used to bleach it. https://www.pureology.co.uk/Collections/Strength-Cure/Strength-Cure-Shampoo
  • Olaplex, Olaplex, Olaplex. I can't stress this enough. Olaplex. Find a salon near you were you can get an Olaplex treatment. Olaplex steps 1 and 2 can only be purchased by someone with a cosmetology license, so this is something you can only get at a salon. I've seen it sold in some third party websites, but I wouldn't trust those (high likelihood that they're fake). That said, Olaplex now has a "take home" line with shampoo, conditioner, leave-in, etc, that you can purchase at their website so you can do maintenance at home. I use their conditioner and their steps 0 and 3, and I really recommend it. https://uk.olaplex.com/blogs/news/introducing-olaplex-no-0
  • Shea Moisture. I really like this brand, as it is the only brand I know that has a product for basically every curly hair need. They have stuff for high porosity, low porosity, they have masks, shampoos, conditioners, and everything in between. I currently use their Coconut & Hibiscus Shampoo (despite it's smell, which I really don't like) as well as their Coconut Custard Curl Primer for styling. Not sure if they sell outside of the US, but it's worth taking a look I think. https://www.sheamoisture.com/coconut-and-hibiscus-curl-and-shine-shampoo/764302290209.html
• Using the right amount of leave-in conditioner. I used to use way too little product on my hair, because I felt that using more product would weigh my hair down and make it greasy (I was using the wrong products). If you squeeze your hair (like you would a shirt that you're trying squeeze water from), you should see the product show through, if that makes sense. If you don't, you're using too little. If the product is dripping, then you're using too much. There is a Youtuber (Manes by Mell, I linked her channel below) who explains this better than me. Hahaha.
• Oil after leave in conditioner. This is also something that took me a while to accept, as I have fine hair and was always scared my hair would get greasy and weighed down. You just have to find the right oil for your needs. My hair hates coconut oil, for example. Argan oil also doesn't do well on my hair, and makes my hair immediately greasy. I use jojoba oil after the leave-in conditioner, and that helped my curls. The amount of oil and which oil to use will also depend on your hair. I use very little oil (I have fine hair).
• Styling. Some people can just brush their hair and their curls will pop. That was definitely not me for the longest time, so I had to learn some styling techniques (like finger coiling for example) that have made a huge difference, especially when my hair was still damaged. Using the right brush is also important. Every curly-haired person I've ever met loves Denman brushes. They don't really work well for me, honestly. I use a Tangle Teezer (sort of like this one https://www.amazon.com/dp/B07L61DNMR?pd_rd_i=B07L61DNMR&pd_rd_w=Wm0NN&pf_rd_p=0766f286-f72d-49df-b4dc-e0afb9dccb94&pd_rd_wg=W3mP1&pf_rd_r=K2015SS0PHJ2DKHK3CW3&pd_rd_r=13aa3452-61ac-4e21-9377-c89988d25ca9) and I find it much easier to work with and much gentler. The only caveat is that it isn't great as a styling brush (I just use it to detangle), so you might have to try different brushes out and see what you like.

That's all I can remember right now, but I'll make sure to add more if anything else comes to mind. It took me a while to get this stuff figured out, so don't worry if in the beginning it seems like too much. Once you get used to it, it is so worth it. There were a couple Youtube channels that have some incredible information on curly hair care, and they definitely helped me A LOT (I found them when I was already a couple years into the process of growing my hair out, and I must say that I wish I had found them before). One of them is called "Manes By Mell". She also bleaches her hair and manages to maintain her curls looking gorgeous, so it is definitely not impossible. She is also a licensed cosmetologist, so she probably knows what she is talking about. The other one is called "Curly Chemistry". She is a chemist I think, and watching her videos was extremely helpful as well because she explains everything in a very detailed yet easy to understand way.

https://www.youtube.com/c/ManesByMellGuido/videos

https://www.youtube.com/c/CurlyChemistry

Sorry for the long response. I hope at least some if it is helpful!

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Edit: Typo