Back in the day when mostly there was Revell, AMT, and MPC car kits available, the few Tamiya kits were “Complex” and challenging. I built the Lotus and was amazed how cool it looked when completed.
After applying a coat of Gunze H30 Gloss Clear, diluted to 70% with nitro as usual (something I’ve been doing for years),
This happened to some parts of the bodywork.
It seems the solvents in the clear coat attacked the previous finish . If you wanted to put in the effort, I think you could save it by sanding and refinishing and new decals . Perhaps staying with one brand and type of finish.
Was the clear a lacquer ? If so it was put over an enamel. Lacquer over enamel don’t mix. If you use enamel base the clear should be either acrylic clear or for some reason testers lacquer clear works too.