John Gill Commentary Leviticus 15:26

"Every bed whereon she lieth all the days of her issue shall be unto her as the bed of her impurity: and everything whereon she sitteth shall be unclean, as the uncleanness of her impurity." — Leviticus 15:26 (ASV)

Every bed whereon she lies all the days of her issue shall
be unto her as the bed of her separation
As defiled and as defiling as that, (Leviticus 15:20Leviticus 15:21) ; and whatsoever she sits upon shall be unclean, as the uncleanness
of her separation ;
as such were when she was in that condition, see (Leviticus 15:20) .