Bootstrap - Class Inconsistency

MSP and LSP in the navbar both refer to a class bg-body-tertiary that refers to a css variable --bs-tertiary-bg-rgb. The colour comes through differently in each app.

1. identify a discrepancy in Bootstrap version
$yarn info bootstrap version / $yarn why 
alternatively for MSP (as bootstrap is managed by gem, not by node_modules)
$bundle show bootstrap [bootstrap version shown in gem path]
bootstrap version 5.3.0, MSP
bootstrap version 5.3.7 LSP

2. css variable defined in (LSP)
node_modules/botstrap/scss/_root.scss
  --#{$prefix}tertiary-bg-rgb: #{to-rgb($body-tertiary-bg)};
so --bs-tertiary-bg-rgb
[function rgb defined in _functions.scss]

or equivalent place in gem (MSP)

3. solution (this specific issue only)
In LSP add $tertiary-bg: rgb(248, 249, 250) to config/_variables.scss;

more generally
change LSP package.json from "bootstrap": "^5.3.7" to "bootstrap": "^5.1.3",