⏺ No, that's not brace expansion for two reasons:
1. It's single-quoted. Bash performs no expansion (brace, variable, glob, etc.) inside '...'. The whole
string max:service.reqs{env:iad1} is passed literally to pup.
2. The content wouldn't expand anyway. Brace expansion needs either a comma list ({a,b,c}) or a sequence
({1..5}). A single token like {env:iad1} has no comma or .., so even unquoted bash would leave it alone