The Bulgarian citizenship law was first amended in March 2021, along with the law on the foreigners in Bulgaria. The second amendment happened in April 2022, which basically terminated the option to apply for investment citizenship in one year after the investment is done. Luckily, the parliament left the option for investors who obtain Bulgarian Golden Visa to apply for full citizenship in 5 years from the start of the application. So in short, the answer to your question is "yes, you can invest" if you want to obtain Bulgarian permanent residence by investment and later for citizenship.
