My font keeps changing in my design. What to do?

When I enter a file, very often all my fonts changed from Helvetica Neue to a random font skinny font. If I click on the font, it changes back to Helvetica Neue but with a thicker stroke.

So let’s say I enter a design file and I see that all the fonts have been changed by Figma, if I had originally set my font to Helvetica Neue LIGHT when I click the font, it changes to Helvetica Neue REGULAR. The font was a completely different font before I clicked on it and the font I had originally set it as doesn’t stay. So it’s frustrating having to go screen by screen, clicking all the fonts, having them change to Helvetica Neue, and then changing the stroke after.

How do I fix this? please help!