Hi there,
this may be less of a bug but a hardware problem but I want to mention it anyway.
With Affinity Photo 1.9, exporting an image seems to be incredibly slow with liquify masks applied.
The two devices I have and I have tried with are:
iMac mid2011 21" quad 2,5GHz i5 16GB RAM with High Sierra 10.13.6 (yes, its incredibly old and I am working on replacing it. But its still my main device for now and it runs incredibly smooth with everything).
MacBook Pro start2015 13" dual2,9GHz i5 8GB RAM with Catalina 10.15.7 (not really a workhorse but my little pal in the field).
Exporting images without liquify masks is still fast as ever but as soon the smallest change with a liquify mask is applied the CPU runs on max for two or three minutes to export the image.
Does someone else has experienced the same?
Since its a very new feature I do somewhat hope that there is a more efficient way to implement that feature without requiring unusual more hardware specs.