Is there anyway to change the default severity to error for every check, without needing to explicitly set it for every ruleset?

Did you try to configure

warningsAsErrors = true

in the detekt yaml config file? https://github.com/detekt/detekt/blob/fc5c993f5df7a84fed527cfa148422690e3e463f/detekt-core/src/main/resources/default-detekt-config.yml#L10-L14

Thanks, but for some reason, that does not work for me. Severity is still reporting as

warning

in the XML report. (Using version 1.19.0)

This was discussed in https://github.com/detekt/detekt/discussions/3942 - Globally configure the severity wasn’t built