Are any of the voluntary contributions to changemakers subject to any kind of tax (income tax, VAT, etc.)?

Tax liability for obtained voluntary contributions is generally the case only when those contributions are made in exchange for completed services provision by a changemaker. In most of the cases it will not be the case, especially if a contribution is serving the purposes of covering the costs of recreational activities of a changemaker. If the contribution was regarded as services exchange, then it would be subject to certain tax allowances (for example income tax: EUR 11 000 per year for all taxable incomes, VAT: EUR 30 000 per year for all revenues; version of march 2018). It is recommended to get professional advice for tax-related matters.