I won't worry that Bangladesh will turn unfriendly towards China, they have no reason to, and they need China to get out of whatever economic crisis they are in. I more worry about Bangladesh falling into anarchy, that is not good for business.
Myanmar is too fragmented and they knew the price of crossing China, and no, I didn't say China should turn it into a puppet state, but China need to make sure to have a navy base foothold there, whether through rent or playing hardball whatever. One thing the uncle sam got it right is that there is no compromise when it came to national security, even if you have to betray your own principle.