The claim presented is false when diving deeper into the linked article you will find that the piece is built fundamentally off of the opinions of Dr. Bhakdi and not proven studies.
Nebraska Medicine released an article debunking this claim with Dr. Cawcutt stated that there is no solid evidence to back up the claim that mRNA vaccines (covid-19) cause any brain damage let alone irreversible brain damage. The article mentions one case where a Parkinson's disease patient's condition worsened after receiving the Covid-19 vaccine, due to preexisting conditions of the patient and only one reported case out off all the covid vaccinations given the conclusion can not be drawn that mRNA vaccines cause irreversible brain damage. https://www.nebraskamed.com/COVID/you-asked-we-answered-do-covid-vaccines-kill-brain-and-heart-cells
USA Today dives deeper into debunking this claim with an explanation on how Covid-19 (mRNA) vaccine was made. The Covid-19 vaccine did not contain the live virus of Covid-19 instead the vaccines were dead viruses used to train the immune system to create corresponding antibodies. The article states that live Covid-19 when put into the body can cause brain damage however the dead virus in the vaccine is not capable of irreversible brain damage.
https://www.usatoday.com/story/news/factcheck/2023/05/19/covid-19-vaccine-not-proven-to-cause-brain-damage-fact-check/70229793007/
A Neurological Events Reported after COVID-19 Vaccines published by PubMed dived deep into the statistics of people injected with the Covid-19 vaccine and the amount of people who reported neurological side effects. Approximately 0.03% of recipients reported a neurological side effect. The article goes on to state “Reports of serious neurological events following COVID vaccination are rare [and] GBS, CVT and seizure may occur”. This research contradicts the claim of “massive, irreversible brain damage”
https://pubmed.ncbi.nlm.nih.gov/35233819/