I have watched an interview with an economic analyst arguing that Romania is in a strange situation ("conflict of interest") because the Constitutional Court members are able to decide about their salaries and benefit (no checks about it).
This article confirms this idea (translated from Romanian):
After the MPs adopted the law that drastically cuts the service pensions that reach fabulous amounts, even 15,000 euros per month, the People's Advocate and the Supreme Court challenged the normative act at the Constitutional Court. The decision is now in the hands of RCC judges, who, of course, also receive special pensions.
This Venice Commission document seems to suggest that not touching judges' salaries is generally prohibited in most countries, except under very special conditions:
The Constitutional Courts or other institutions implementing the constitutional supervision, have established that in a situation when a state experiences financial difficulties, the judges salaries must be especially protected against excessive and adverse fluctuations (Poland)
Similar statements were expressed by Constitutional Court or similar institutions from other countries such as Lithuania, Latvia and Slovenia.
While the Romanian analyst argued about the conflict of interest of setting your own budgetary salary and benefits, this does not seem to be supported by practices in other countries.
I am wondering if any European country legislative body has ever managed to reduce the salaries and/or benefits of judges on the Constitutional Court (or similar body)?