R Markdown with \newif fails to compile to pdf after update

Question

After the latest update to RStudio "Ghost Orchid" (Build 372) the RMarkdown below fails to compile to pdf on macOS Monterey. An identical file compiles fine on a different machine running previous versions of both RStudio and macOS ("Juliet Rose" (Version 1.4.1717), macOS Big Sur).

Any help to fix the problem is highly appreciated, thanks!

---
title: "minimalTest"
output: pdf_document
---

``` {r, include = F}
solution <- TRUE 
    ```

\newif\ifsol
\sol`r ifelse(solution, 'true', 'false')`

# Simple example of non-compiling code

\ifsol

Text to conditionally skip

\fi