We've had issues with Klipper immediately stealing the clipboard whenever it gets updated from the server. This can result in incorrect contents, and even non functional clipboard in either the client or server. Report upstream: https://github.com/TigerVNC/tigervnc/issues/520 And fix upstream: https://github.com/TigerVNC/tigervnc/commit/dfc2001b3f681cbd1377a3096781182727f13d24 Apparently this was a general Qt bug that would affect any application using that toolkit. A workaround was possible in Xvnc though.
Verified that I could reproduce the problem with interfering klipper using ThinLinc v4.9.0. Upgraded to nightly build and there is no apparent interference with klipper and clipboard.