After my buttercream is made, I take my rubber spatula and kinda macaronage it. I’m terrible at explaining, but you’re just folding the buttercream into itself until all air bubbles are gone. It works best for me because the consistency of the buttercream doesn’t change much!

A hack that always works for me - remove 1/3rd of the buttercream onto a separate microwave safe bowl, warm it up for 10 secs, add it back to the rest of the buttercream and mix it altogether with a flat silicone spatula.

I have two buttercream tips on my page I can send you