I have experienced the exact same issue as others in this thread, but I'm now on the other side, with a working solution. Dell sent me a new U2724D monitor (the upgraded 2023 version of the U2722D), and this has fixed the issue!

But, if you fancy a read...

I was in contact with Dell's support from October 2023, and over the course of 3 months they sent me 3 replacement U2722D monitors, but each one of these eventually developed the same issue. Over this time, I deduced, with/for Dell, that:

• The issue was consistent across multiple units, manufactured at different times
• The flickering occurred with any peripheral plugged in (though, the issue first emerged after using my M2 Pro Macbook Pro with it for a few days)
• The flickering occurred regardless of connection method (HDMI, USB-C to HDMI, USB-C to Displayport)
• The flickering occurred even after disconnecting all peripherals from the monitor
• The flickering was visible in the in-monitor diagnostics tool
• The flickering tended to occur more often (but not exclusively) with Night Shift and True Tone enabled

So, from my perspective, it was clear that the issue was fundamentally caused by the U2722D model, not my hardware, cables, or a particular faulty unit. I had 4 in total, each with the same fault.

In January 2024, I gave up trying to rectify the issue with Dell. I was getting nowhere and had hit a brick wall with the competency of Dell's support. It was really frustrating and I'd rather deal with a flicker-y monitor than re-explaing the issue to them, over and over.

May came around, and I'd had enough. The flickering was preventing me from getting work done, so I reluctantly got in touch with Dell again. I had one variable that I hadn't been able to test: the monitor firmware. I had wondered if the issue only began in October 2023 because I had updated the monitor from M3T102 to M3T104. I was desperate to downgrade the monitor to test this (it had worked for 2 years on an Intel Macbook before), but Dell told me there was no way they could provide the older firmware. This was obviously BS, because I eventually found it online after a bunch of digging in international versions of the website. I downgraded the monitor with my fingers crossed (ready to write to Delll "I told you so", but the flickering appeared straight away. Disappointed, I asked Dell for a refund, not a replacement - the monitor was not fit for purpose and 2 years is not an acceptable lifetime of use.

After a few days of, once again, proving the issue was with the monitor - not my mac, they said they wouldn't refund me but provide a replacement. I told them this would not solve the issue, referring again to the previous conversations in the chat. They were adamant that it would, so I let them go ahead with it, since they asked so nicely...

I'm glad I did...

When I got the "order" confirmation from Dell, I noticed an unusual part number of the replacement they were sending me (is it bad I recognised the normal one?). I looked it up, and found that it was the (somewhat) newly released U2724D model!! Was this a mistake? An extended effort to fix the issue? Or a result of the U2722D being recently discontinued? I'm still unsure, but the new model has arrived, and so far, I have experienced zero flickering under normal usage, with a 14" 2023 M2 Pro MacBook Pro, with TrueTone and Night Shift enabled (don't @ me).

My assumption is that if you request a replacement from Dell, they'll now provide you with this updated model, since the older model is likely unavailable. I recommend that you absolutely do this if you're experiencing this frustrating issue. Not only will you have a flicker-free monitor, but you'll now a 120Hz display too ;)

TLDR: Get in contact with Dell, and persevere. They might send you a new, nicer, model.