To be precise, I have seen this in 14.0-RC2 and 14.0-RC3. in 13.2-RELEASE this has worked without problems. When installing linux in bhyve, using "https://klarasystems.com/articles/from-0-to-bhyve-on-freebsd-13-1/" as a guide, the mouse freezes in VNC. This makes installing any distro using a pure grphical installer (e.g. MX linux) impossible to install. If I install void linux so I can run startx, I can type commands in xterm using VNC, but I cannot use the mouse. I have had the same result using tigervnc-viewer and remmina.
Forget abnout this bug, it was just a settings issue.