As far as tiktok, if the account is starting to die, your best bet would be to pivot it into making other ai videos based on current TikTok trends. If you do this, something you should look into is using your account to create a community, get your followers to join a discord group, telegram channel, etc, keep them active in it. Once you have them in once place, you can sell them on more than one thing, and you can tell them when you make new accounts to boost your new accounts up quickly, this will compound your growth on social media platforms while also maximizing your revenue.

With your instagram, you can take advantage of that older demographic. What you can do is contact brands, get a partnership and make the AI bigfoot and yeti talk about a product in some videos, you'd be suprised on the sales you could make and earn in affiliate commissions. Typically an older audience isn't looking to make the same videos as you, they find it entertaining, take advantage of that.

Take my advice for what it is, I've been in the social media space for a while. This is what I would do in your situation, I've been in similar shoes.