Keto lupin bread issues

Hey!

Few years back I used to make a keto bread with lupin flour from THIS RECIPE

It was great, for sure best keto bread I've found. At the beginning it was great. It was not crumbly, toasted perfectly. Was basically like a nice wheat bread, only difference was that I was not able to get anything remotely resembling typical, thick and crunchy crust. But whatever, it was great (pic below)

How it started

I used this recipe for about a year, then I gave up bread for some time, just didn't feel like baking and ate different things. After couple months I started baking again, but it was getting worse and worse. Biggest issue I have with this bread now is that it just can't support itself. Dough is nice, rises nice, looks great after baking, but right after I get it out of oven it just cannot support itself and it collapses.

How it looks now

I have no idea what's the issue. I tried baking it longer in lower temp. I tried baking it shorter in higher temp. I've changed ratios between lupin, oat fiber and wheat gluten (the result on the pic is when I tried increasing gluten significantly). I tied also increasing and decreasing the moisture of the dough. I'm now clueless. I have no idea what changed and what to do. I'm starting to think that maybe it's somehow related to the ingredients? But I've also doublechecked and tried using exactly the same brands I was using at the beginning (though I have no idea whether they changed anything).

I'd be thankful for any suggestions, tips, ideas or even alternative recipes for lupin bread.