I'm also facing this problem in my model's development, currently, I'm using the Thin Plate Spline (TIN) algorithm as a replacement for QGIS' native TIN algorithm or the Multilevel B-Spline depending on my needs.
I think you should post a bug report as that's not the intended behavior.
See https://github.com/qgis/QGIS/issues/30029, as of 3.22.11 LTR this bug hasn't been resolved, the workaround is using SAGA TIN for a drop-in replacement (albeit with different result compared to the native algorithm).
Edit: I'm currently using Triangulation [saga:triangulation]
from SAGA (https://saga-gis.sourceforge.io/saga_tool_doc/7.8.2/grid_gridding_5.html), which need a point layer. So, as an intermediate, I'm passing the vector layer to Vector geometry -> Points along geometry [native:pointsalonglines]
with 2m spacing. Both works in model builder and result in an otherwise identical result (to the naked eye, and in my case, after converting back to contour line) to qgis:tininterpolation
.