Sorry for not responding in June, I didn't get a notification until now.
I created a new ticket https://bugs.mojang.com/browse/MCPE-142813 and added the missing description on the report. thank you.
I also had the same issue and this problem has been fixed in the 1.16.0.68 beta, meaning that when that comes outs the sign-in issue will also be fixed.
I thought it was a little slower to mine than normal stone, not as it were a leaf.
As reading the wiki 1.17 (java section), but knowing about it since MCPE-102759. prior in bedrock.
(21w18a Instead of breaking instantly, infested blocks now take half of the time to breaks compared to their regular counterparts.)
(21w19a Pickaxes are now the appropriate tool for breaking infested blocks)