I do not want to defend those here at all costs, but the top 10% bear about 50% of the tax burden (if I remember correctly)
That’s roughly correct.
According to the Socio-Economic Panel, Institute of the German Economy 2018:
2.5 million taxpayers with monthly income >20,000€ paid 99.2 billion € including solidarity surcharge
2.0 million – 15,000-20,000€ – 33.9 billion €
3.9 million – 10,000-15,000€ – 46.9 billion €
11.3 million – 5,000-10,000€ – 81.2 billion €
29.9 million – 1-5,000€ – 59.5 billion €
26.6 million – 0€ – 0€
What supports the statement of is a publication by the Federal Ministry of Finance, which shows that the group with an annual income between 70,000 and 250,000€ pays the highest average rate. With increasing income beyond that, the rate dramatically decreases to less than half—so much so that a millionaire on average pays income tax at roughly the same rate as someone with an annual income of 50,000-60,000€.
Therefore, there is no contradiction in these statements according to the data.