Waggy square on trocen AWC7813

Anyone know why i get this waggy square
? It’s on X axis.
I have checked mirror and lens and all are tight enough. Belt already checked as well.
I use trocen AWC7813

So I had a very similar thing happen to me.
In my case it had to do with dirty side rails.
I cleaned all the grease from the side rails and any where else that I found grease and instead of applying new clean grease I just use silicone spray.
I’ve not had that problem since then.

I will check again my x axis, thanks.
Actually kind of weird I have problem with x axis since my x axis using linear rail while y axis still using only roller