Plenty of people have posted their Instagram profile links in their Twitter bios over the years and never got suspended or locked for it. I've posted tweets with links to my Instagram profile several times and never got even a warning. This is all new Musk policy.

I’ve definitely linked to my profiles on other sites before and never been banned or even warned.

There’s been reports of mastodon links being handled oddly for a while prior to this announcement. Not insta though. Odd Twitter considers them a competitor though Insta did get big through twitter originally.

If by "a while" you mean the past handful of days, then yes. To suggest that this has been an unspoken policy for years is simply wrong and misleading.

For a while? I've only heard of that in the past few days.

I more mean “on various occasions over the last several years”