It happens with any browser. It degrades until any operation carried out takes several seconds. If I deactivate the extension everything returns to normal.
The last update of the extension solves the problem.
1.4.2 (16 April 2020)
[-] Logging in to Plesk using the Google Authenticator mobile application many times over a short period of time no longer results in long loading times for Plesk pages. (EXTPLESK-1787)