Before I add --legacy-wintab
This is all the step I did:
1. When Chris said Windows Ink will not matter if it is enabled or disabled then I enabled back all windows ink setting from:
A. Wacom app setting > Mapping > Turn on Windows Ink.
B. Turn on visual effects in the Pen and Ink settings on Windows through “Windows settings”> “Devices”> “Pen” or “Pen & Windows Ink”> Enable “Show visual effects” and “Show cursor”.
C. Go to “Control Panel”> “Tablet”> “Pen Options”> “Pen and Touch”> “Press and Hold”> “Settings” and Check “Enable press and hold for right-clicking”> “OK”;
2. On another thread, Dan told me to reset affinity photo.
Push Left CTRL key while opening Affinity Photo, reset window will open, select all, then reset.
(it will remove every custom brushes, shortcut, etc)
3. Add --legacy-wintab
After step 3, it doesn't lag anymore and my wacom pen hard button (the button on the pen) works like it should be.