If you watch a longer,
2-minute footage, you can see that after the strike at the end of the video, the boat didn't sink, but continued to swim.
Is there any evidence that these boats sank afterwards?
Straw man. Bayraktars can kill tanks, chances are the boat - even if it's still floating - is done for.
The Russian side
Do you seriously believe that "the Russian side" would say "yeah we dropped a bomb on it" even if they did?
AP is the closest we have to an independent investigation.
Under this video, one user left a comment, that it was a Russian retaliatory strike on a Ukrainian howitzer.
LOL, that makes it true obviously

Just like every building in Mariupol was Azov HQ.