Thanks for your reply. I just wanted to show you a way to reproduce this problem. In any case, I succeeded in this way. But we see that this bug occurs not only for me, and perhaps the matter is not at all in the "Photoshop" program. Perhaps this is just one factor that influences this behavior of the mIRC client. Other users probably have something else affecting the appearance of a similar bug, but they have not yet found the cause.
And only because other users have already complained about the same bug, I wanted you to be able to reproduce this yourself to see what it looks like and try to study the problem. This bug appeared after "mIRC v7.63
There are many ways to do that, if you could give exact steps, like if you have an on start even with some /server command, give your on start, the switch on /server like -jn could be the cause.
In this testing, I set up auto joins to channels through the "Favorites" button on the top "Toolbar".
But you can also use the command for connect so that detection the bug: "/server irc.yourserver.com 6667 -i user user_ user@email user -jn #test,#test2