UI not responsive until postgresql restart

I use pgadmin 4.10, postgresql 11.3 on Fedora 30.

Whenever I log into pgadmin for the first time in a session, I can't move around in the databases and it keeps "loading" with loading circles in the tree layout.

To unblock this, I found out that running "sudo service postgresql restart" solves the issue immediately, and then everything works fine.

Here is the stats dashboard just after the restart, when everything goes back to normal:

You can see there is a huge spike, and it must be the reason why it gets stuck.

On similar occasions, I already saw such charts, with the number going symetrically (like a sinus) in similar positive & negative values.

It is not a huge pain, because restarting the server fixes the issue. But maybe there is a way to avoid / fix this altogether? Or investigate? Or it's not on pgadmin side?

Best,

Michael