I'm having a strange little graphics bug. It doesn't spoil gameplay - the game only looks somewhat worse - but I just wonder if anyone else also has it. In some levels of the Lagoon the screen is flashing in a certain way: two shades of dark blue (including the color of the water at this stage) become pale blue instead. Some levels are indeed "flashing" - these colors turn pale for a while and then back - but some levels (6, 10...) actually have altered colors all the time. No such effects on other stages of the game.
I'm pretty sure I didn't have this bug when playing "Fury of the Furries" in native DOS in the 90s.
Another weird (but pleasantly surprising) aspect is that it doesn't affect screenshot capture: when I used the D-Fend Reloaded screenshot capture keys (Ctrl-F5) while the colors were altered (it was level 10, so colors looked like this during the whole level), the screenshot had unaltered colors anyway.
As said, it just doesn't look as good as with original colors, but has no influence on gameplay, however I don't recall having this bug in the 90s and I wonder if other people have noticed it too.

Self-reply: I observed the bug a little more (nevertheless, it IS some bug) and after trying out the Amiga version as well I was able to make a comparison. Those two bright shades flashing in the screen are shades used in shading clouds and the screen flashes whenever the Furry is on a level (in the "geometrical", not "gameplay" meaning - "altitude", not "stage of a game") which would make the clouds visible. They don't have to be necessarily visible, but if there are clouds on a level (I think the only cloudless levels in the Lagoon are levels 7 and 9), the screen will flash (that's why for example level 2 is too bright all the time - it's only one screen high). As D-Fend Reloaded seems to correct this bug out of some reason, the clouds will look bad, their edges will be too dark because they will be "corrected" too. So the essence of this bug seems to be some confusion of two bright blue shades used only for cloud shading and two dark blue shades used for water and background. Anyway, this bug doesn't appear in the Amiga version and, as I wrote, I also don't remember it appearing in the native DOS version in the 90s.

Did you try different graphics adapter emulations? There are some to choose from, from early plain VGA to later SVGA versions. Possibly the issue occurs only with some of them?

I didn't notice the reply... Anyway, I could try it, but I don't know how. I use D-Fend Reloaded - do I have to make some changes in the profile's "Graphics" section?
The Polish guys who make Windows-playable "execs" of Amiga games (with an in-built emulator) noticed that while it's of course VGA, only 16 shades are used in a level at once. But I have no idea it if has anything to do with this bug, I would have to try counting the shades "with" and "without" this bug.

I use D-fend reloaded too (it's almost always enough).

With the profile editor for the FotF game, select graphics seciotn on left, and in the right pane you'll see a clickable box for the video card selection, listing the emulated VGA cards. standard VGA/3 different S3 versions/2 Tseng Labs cards etc. Select one and click OK to save it, start the game and try loading one of the problem areas.

I tried the FotF game for fun, but never got as far as the areas where the glitch might appear. (I'm not so good at platform jumping)