Before you could add up to ~9k bytes using one TXT record, now it seems to give errors above 3k bytes
yes I think they have halved the maximum size without notices or switched encoding that consequently reduced max size ?
What type of TXT record are you having the issue with?
Plain data, no spf,dkim,etc.
You can try posting it here and someone should be able to take a look or you can contact support.
You can reproduce it simply by creating a TXT record and adding multiple strings.
I can only tell you could store as many strings to reach 8kb data previously, and now you can only store 4kb there isn’t much else to provide, it’s an undocumented limit, infact there is no information about how many txt records can be chained, and since cloudflare doesn’t provide documentation I guess they can change the limit as they please as they consider it an edge case or a plus or whatever