Hmmm, there seems to be errors in building the website.
Perhaps a problem with the < escaping process?

I checked altdoc:::.rd2qmd("man/DataFrame_sql.Rd", ".", ".").
The output qmd file has this:

# Apply transformations to a DataFrame using SQL, aliasing "self" to "frame".
df1$sql(
  query = r"(
SELECT
a,
(a \% 2 == 0) AS a_is_even,
CONCAT_WS(':', b, b) AS b_b,
EXTRACT(year FROM c) AS year,
0::float AS 'zero'
FROM frame
)",
  table_name = "frame"
)

\% should be replaced to %.

Apparently this is a bug in roxygen2. The following Rd file is fine, so no % escaping is needed here.

\examples{
a <- "\%"
b <- "
%
"
c <- r"(
%
)"
}

I opened an issue r-lib/roxygen2#1616

For now, we can use MOD(x, 2) instead of x % 2 to avoid using % in examples.

This is a new experimental method addition that does not affect existing code.
So merging.