Theme have different looks within same language

[HartmannsgruberBen]

Hello folks,

I have noticed a strange behavior and I can't explain it.
I am using helix with the kanagawa color theme.
I use it to develop .ts files and tests .spec.ts.
The color theme looks different (backgroundcolor) in .ts than in .spec.ts.
What causes this behavior?

~/.config/helix/config.toml
theme = “kanagawa”

~/.config/helix/languages.toml
[language-server.typescript-language-server]
command = “npx”
args = [“typescript-language-server”, “--stdio”]

[[language]]
name = “typescript”
scope = “source.ts”
file-types = [“ts”, “tsx”, “spec.ts”]
roots = [“package.json”, “tsconfig.json”]
language-servers = [“typescript-language-server”]
auto-format = true

[[language]]
name = “javascript”
language-servers = [“typescript-language-server”]
auto-format = true

if I set a different theme directly in the editor using :theme xxx, this also looks different.
Where does this come from and how can it be adjusted?