get_variance() reports incorrect variance for brms logit models

[devincaughey]

I think that insight::get_variance() reports the incorrect residual variance for logit models from brms (and possibly other packages). It reports the variance as 1 (which is correct for a probit model), but it should be $\pi^2/3$ for bernoulli or ordered logistic models. Based on some quick detective work, it seems that the source of this problem may be insight:::.compute_variance_distribution(), which uses 1 as the default value. See the following lines:

    if (is.null(sig)) 
        sig <- 1

and

        else {
            dist.variance <- sig
        }

[strengejacke]

Do you have a reproducible example? get_variance() not only includes sigma, but other variance components from mixed models as well. In the case of logistic regression, pi^2/3 is used as distribution-specific variance, see:

insight/R/compute_variances.R

Lines 504 to 515 in ddb8c4a

	} else if (faminfo$is_binomial) {
	# binomial / bernoulli ----
	# --------------------------
	dist.variance <- switch(faminfo$link_function,
	logit = pi^2 / 3,
	probit = 1,
	cloglog = ,
	clogloglink = pi^2 / 6,
	.badlink(faminfo$link_function, faminfo$family, verbose = verbose)
	)
	} else if (faminfo$is_count) {