For years, I've been rolling over 0% BT offers from one card to another every 12-18 months. In the interest of lowering utilization on one card <30%, I took a look at some of my existing cards that always seemed to have a 0% BT offer going (with 3-5% fee) and nothing was available. I assume this is banks being cautious in the current pandemic.
I know Citi (and maybe others) are still advertising 0% offers on new cards. Incidentally, I've found that Citi and Amex have been pretty conservative lately on the size of the credit lines they extend on new cards with 0% BT offers - the last cards I opened for a BT with each bank came with significantly lower limits than they tend to give me on non-0% BT cards (though they weren't always so conservative with their 0% card offers). For rolling over medium/large size balances, it has been convenient in the last year to use existing card lines rather than new cards that might have limited credit.